How can huntingtons disease be inherited

Although different sources vary slightly in describing the significance of CAG repeat numbers, the following explanation is based on information from the well-respected genetics website, Gene Tests:. The number of CAG repeats you have gets determined at conception and is not expected to change over time.

However, the gender of the parent you inherit an HD expansion from may play a role in determining the number. If you inherit the HD-causing gene from your father, the number of CAG repeats may increase, expanding as the gene is passed from father to child.

But if you inherit the gene from your mother, the number of CAG repeats usually remains stable. This is significant because the number of CAG repeats plays a role in the age of onset. In general, the higher the number of CAG repeats, the earlier the onset -- although exceptions occur regularly so this is only a general guideline. Other genetic and non-genetic variables also contribute to the complex issues that determine the age of onset and severity of symptoms.

Toggle navigation. George Huntington was an American physician who contributed the clinical description of the disease in Learn more about Dr.

Huntington and the early efforts to understand HD. History and Genetics of Huntington's Disease Reports on the neuropathology of chorea in adults appeared as early as the s, with researchers generally agreed that the basic lesion was located in the basal ganglia. Contact Us. Inability to speak. Voracious appetite. Muscle rigidity. Degeneration of cerebellum. Dementia, progressive. Progressive dementia. Inability to coordinate movements when walking. Increased reflexes.

Loss of brain cells. Personality change. Do you have more information about symptoms of this disease? We want to hear from you. Do you have updated information on this disease? Cause Cause. This gene gives instructions for making a protein called huntingtin. The exact function of this protein is unclear, but it appears to be important to nerve cells neurons in the brain.

This segment is made up of three DNA building blocks that repeat multiple times in a row. In people with HD, it may repeat from 36 to over times. People with 36 to 39 CAG repeats an intermediate size may or may not develop HD, while people with 40 or more repeats almost always develop HD. Inheritance Inheritance. Huntington disease HD is inherited in an autosomal dominant manner. Most people with HD have an affected parent.

The family history can sometimes appear negative for various reasons even though a parent carries, or carried, a mutation in the HTT gene. In rare cases, HD is caused by a new de novo mutation in the HTT gene, in which case the disease occurs for the first time in the affected person and is not inherited from a parent. A longer repeat in the HTT gene may cause earlier onset of symptoms.

This phenomenon is called anticipation. Diagnosis Diagnosis. A diagnosis of Huntington disease is typically suspected in people with characteristic signs and symptoms of the condition and a family history consistent with autosomal dominant inheritance. The diagnosis can then be confirmed with genetic testing that identifies a specific type of change mutation in the HTT gene. The intended audience for the GTR is health care providers and researchers.

Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

The Division of Neurogenetics at the University of Washington is a tertiary specialty that provides clinical services to adults in the general public as well as training.

They have created a booklet entitled, " Huntington Disease: Making an Informed Choice , that can be downloaded at no charge. Orphanet lists international laboratories offering diagnostic testing for this condition.

Treatment Treatment. Unfortunately, there is currently no cure for Huntington disease HD. The current goal of treatment is to slow down the course of the disease and help affected people function for as long and as comfortably as possible.

Depression and suicide are more common among affected people, so caregivers should monitor for associated symptoms and seek help if necessary. As symptoms of the disease worsen, affected people need more assistance, supervision, and care. Prognosis Prognosis. Huntington disease HD is progressive, eventually leading to disability and death usually from a coexisting illness or infection.

However, the disease affects everyone differently; the age of onset, specific symptoms, and rate of progression varies for each person with HD. While the symptoms of HD are well-characterized, their progression especially in the early and middle stages remains unpredictable. With the approach of late-stage HD, affected people have speech difficulty and weight loss. In the late stage, affected people lose bowel and bladder control.

Most people with HD survive for years after the onset of symptoms. The average age at death ranges from years, but the range may be broader. In a large study, pneumonia and cardiovascular heart disease were the most common primary causes of death. However, there is still a lot of variability. Both genetic and environmental factors are thought to play a role on the age of onset in people with a mutation.

Inheritance through the father can lead to more repeat expansion and earlier onset through succeeding generations, a phenomenon called anticipation. Find a Specialist Find a Specialist. Healthcare Resources To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself.

You can also learn more about genetic consultations from MedlinePlus Genetics. Related Diseases Related Diseases. Conditions with similar signs and symptoms from Orphanet. Differential diagnoses include other causes of chorea including general internal disorders or iatrogenic disorders.

Phenocopies clinically diagnosed cases of HD without the genetic mutation are observed. Visit the Orphanet disease page for more information. Research Research. Clinical Research Resources ClinicalTrials. Click on the link to go to ClinicalTrials. Please note: Studies listed on the ClinicalTrials. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study. Funded by the National Institute of Neurological Disorders and Stroke, a branch of the National Institutes of Health, the Roster computerizes the names of families, including information about the history of HD in the family family trees and other related data.

This information identifies HD patients and families who are interested in participating in research projects. Organizations Organizations. Organizations Supporting this Disease. Do you know of an organization? Living With Living With. In addition, some programs may provide financial assistance for additional expenses related to a patient's diagnosis such as travel to see a specialist. This initiative speeds up the processing of disability claims for applicants with certain medical conditions that cause severe disability.

More information about Compassionate Allowances and applying for Social Security disability is available online. Community Resources The Job Accommodation Network JAN has information on workplace accommodations and disability employment issues related to this condition. Department of Labor. Learn More Learn More. Where to Start MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

This website is maintained by the National Library of Medicine. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.

Click on the link to view information on this topic. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them. In-Depth Information GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.